IEEE 802.15.4 defines the physical layer (PHY) and medium access control (MAC) sublayer specifications for low-data-rate wireless personal area network (LR-WPAN). IEEE 802.15.4 has some similarities to IEEE 802.15.3 that is a standard for higher-data-rate WPANs.
IEEE 802.15.4 standard uses binary phase-shift keying (BPSK) in a band of 868/915 MHz to provide transmission speed of 20 Kbps and 40 Kbps and uses offset quadrature phase-shift keying (O-QPSK) in a band of 2.45 GHz to provide transmission speed of 250 Kbps. IEEE 802.15.4b standard also uses O-QPSK in a band of 868/915 MHz to provide transmission speed of 250 Kbps.
Unlike wireless local area network (WLANs), access in WPANs is efficiently achieved even in an environment that does not or rarely involves an infrastructure. This feature allows a compact, power efficient, and low-cost solution to act on a wide range of devices.
Medical body area network (MBAN), as an example of WPAN, is being discussed in IEEE 802.15.4.
MBAN (Medical Body Area Network)
A medical body area network (MBAN) system operates in a US frequency band of 2360 MHz to 2400 MHz and is limited to a maximum emission bandwidth of 5 MHz.
A frequency band of 2360 MHz to 2400 MHz used in the MBAN system is already allocated for other wireless communication systems. The MBAN system operates on a cognitive radio-based secondary basis. That is, the MBAN system must not cause harmful interference to a primary user and needs to use the above frequency band despite interference from the primary user.
Thus, when the MBAN system operates in a frequency band of 2360 MHz to 2390 MHz, MBAN devices need to operate inside registered healthcare facilities, in principle.
In collaboration with the primary user, the MBAN system needs to control usage in 2360 MHz to 2390 MHz. When the primary user uses the above frequency band, all operations in the above frequency band need to be initialized and to be restarted using a frequency band of 2390 MHz to 2400 MHz.
That is, when MBAN devices move outdoors, the MBAN devices need to stop an operation or to change the frequency band to 2390 MHz to 2400 MHz used as a basic frequency band and to perform communication. When the MBAN devices operate in a frequency band of 2390 MHz to 2400 MHz, the MBAN devices may perform communication both indoors and outdoors.
When the MBAN devices operate in a frequency band of 2360 MHz to 2390 MHz, transmission power thereof is set to a smallest value of 1 mW and 10*log(B) dBm. When the MBAN devices operate in a frequency band of 2390 MHz to 2400 MHz, the MBAN devices use transmission power of a smallest value of 20 mW and 10*log(B) dBm. Here, B is the 20 dB emission bandwidth.